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  <h2 class="title"><span class="function"><a href="function.posix-access.html" class="function">posix_access()</a></span> constants</h2>
  <blockquote class="note"><p><strong class="note">注意</strong>: 
   <p class="para">
    Please note that some of these constants may not be available on every system.
   </p>
  </p></blockquote>
  <dl>
   
    <dt id="constant.posix-f-ok">
     <strong><code>POSIX_F_OK</code></strong>
      (<span class="type">int</span>)
    </dt>

    <dd>

     <span class="simpara">
      Check whether the file exists.
     </span>
    </dd>

   
   
    <dt id="constant.posix-r-ok">
     <strong><code>POSIX_R_OK</code></strong>
      (<span class="type">int</span>)
    </dt>

    <dd>

     <span class="simpara">
      Check whether the file exists and has read permissions.
     </span>
    </dd>

   
   
    <dt id="constant.posix-w-ok">
     <strong><code>POSIX_W_OK</code></strong>
      (<span class="type">int</span>)
    </dt>

    <dd>

     <span class="simpara">
      Check whether the file exists and has write permissions.
     </span>
    </dd>

   
   
    <dt id="constant.posix-x-ok">
     <strong><code>POSIX_X_OK</code></strong>
      (<span class="type">int</span>)
    </dt>

    <dd>

     <span class="simpara">
      Check whether the file exists and has execute permissions.
     </span>
    </dd>

   
  </dl>

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